It prefers well-drained fertile soils, although as it is shallow rooting, it will grow over laterite provided this is more than about a metre below the surface. It does not thrive on swampy sites, or in areas with a heavy growth of Imperata. Young plants are subject to browsing damage by domestic animals. They are killed by fires, but will shoot again from the base. The tree coppices freely and produces root suckers. In the Bhabar Terai it tends not to have a single main stem; it has a spreading crown and many branches. It has a spreading root system, and competes strongly with other species; competition in pure plantations also sets in early, so wide spacing is desirable. Once established the heavy crown eliminates grass competition. Cassia siamea does not form root nodules with Rhizobium species, and hence does not fix nitrogen.